ActionScript3 Errors

[Marty1963]

I'm trying to reuse an old Flash file that my client wants on his website however I'm using Flash CC now, and the existing code does not funtion in ActionScript3. I can't see why this won't work. Any advise would be greatly appreciated

function randRange(min:Number, max:Number):Number {
    var randomNum:Number = Math.round(Math.random()*(max-min))+min;   
    return randomNum; 
}     
var myFrame; 
myFrame = randRange(2,7); 
gotoAndStop(myFrame);